1. Field of the Invention
The present invention relates to a data reproduction protection method, and a data reproduction apparatus for implementing such a protection method, whereby reproduction of a signal represented by digital data such as a recorded digital video signal can be selectively restricted.
2. Description of the Prior Art
In the following, the term xe2x80x9cdata mediumxe2x80x9d is to be understood in a very general sense, as applying for example to broadcasting systems which transmit data such as video and/or audio data, in which case the received data may be the object of reproduction protection, and as applying also to any type of recording medium such as recording disks or tapes, etc., in which case playback data derived from the recording medium may be the object of reproduction protection. The reproduction protection may serve to selectively restrict viewing, hearing or copying of the data.
In the prior art, various types of reproduction protection method have been applied in fields such as CATV (cable television) and satellite television broadcasting. One method is to execute scrambling processing of transmitted video and audio data, and to insert a copyright code into the data, for thereby dividing the data into portions which can be freely reproduced and portions for which a fee must be paid in order to reproduce the data. When a program for which payment of a fee is necessary is received by a receiving apparatus, the program can be unscrambled and reproduced only if specified payment conditions are satisfied.
In the case of recorded media, one method of reproduction protection which is applicable to the DAT (digital audio tape recorder) recording system is the SCMS (serial copy management system). With that method, the playback DAT signal from a DAT playback apparatus has a main ID (identification) number which includes a copy inhibit code, whereby a single [copy enable-copy inhibit] sequence is ensured, so that a user can only make a single copy of a pre-recorded digital audio tape.
However with such prior art methods of reproduction protection there are only two control possibilities, i.e. reproduction is made either possible or impossible. It has not been possible hitherto to provide a gradually varying degree of restriction of reproduction of a signal conveyed by a data medium. Thus, such a reproduction protection method can only be used for a single purpose, e.g. for management of payment fees, or for copyright protection. Moreover with such a prior art reproduction protection method, since the data which are to be protected exist only in a transmitting medium or recording medium prior to being reproduced, it has not been possible to provide a varying degree of limitation of reproduction capability in accordance with some condition of the reproduction apparatus. Thus in some cases, the degree of protection may be excessively severe, or excessively lax, so that it is difficult to achieve an effective degree of protection. For example, certain types of scenes recorded on a video tape may be permitted to be viewed in a certain country, such as the U.S.A., but may not be permissible in other countries. It would thus be advantageous to ensure that when that video tape is played on a reproduction apparatus which is sold to the public in such other countries, reproduction protection is automatically applied such that the aforementioned scenes will not be reproduced, or will not be clearly reproduced. However in the prior art, such a feature has not been possible.
It is an objective of the present invention to overcome the problems of the prior art set out above, by providing a reproduction protection method and apparatus whereby information specifying a degree of restriction of reproduction of an original signal is conveyed (e.g. by a recording medium or signal transmission medium) together with data expressing the original signal, whereby information specifying a degree of restriction of reproduction of the original signal are generated by a reproduction apparatus which operates on the conveyed data, and whereby information specifying a degree of restriction which is actually applied to reproduction of the original signal is derived based on a combination of the restriction information conveyed by the data medium and the restriction information generated by the reproduction apparatus.
More specifically, the invention provides a reproduction protection method comprising: attaching medium protection data to main data which are conveyed by a data medium, said main data representing an original signal;
supplying the main data and medium protection data, via the data medium, to a reproduction apparatus;
generating apparatus protection data by the reproduction apparatus;
determining a protection level by combining the medium protection data and the apparatus protection data; and
controlling the reproduction apparatus to utilize the main data to reproduce the original signal in accordance with the protection level.
It is a further objective of the invention to overcome the above problems by providing a reproduction apparatus providing reproduction protection, for operating on main data representing an original signal and medium protection data expressing a medium protection level, said main data and medium protection being conveyed by a data medium, the apparatus comprising:
means for detecting said medium protection data to obtain a medium protection signal expressing said medium protection level;
means for generating an apparatus protection signal expressing an apparatus protection level which has been assigned to said reproduction apparatus;
means responsive to said medium protection signal and apparatus protection signal for determining a final protection level in accordance with a combination of said medium protection level and apparatus protection level;
means for executing reproduction of said original signal by utilizing said main data, including means for selectively restricting said reproduction in accordance with said final protection level.
With such a method and apparatus for reproduction protection, the protection level can be determined in accordance with the medium protection data, and hence can be determined in accordance with the wishes of the manufacturer of the data medium, or of the copyright owner of the main data. In addition, the protection level which is actually applied (i.e. the final protection level) is also determined in accordance with the apparatus protection data, which can be specified by the manufacturer or the seller of the reproduction apparatus. As a result, when the main data are to be reproduced (for example, during playback of a recording disk or tape), a graduated degree of limitation of reproduction is implemented, with that degree of limitation being determined by the final protection level, i.e. being determined in accordance with a combination of the requirements of the data medium manufacturer or the copyright owner of the main data and the requirements of the manufacturer or seller of the reproduction apparatus. In that way, considerable flexibility can be ensured in selectively restricting reproduction of signals which are conveyed for example by recording disks or tapes or by broadcasting systems.
In particular, the invention enables such reproduction restriction to be applied to specific frames or sequences of frames of a video signal, or to specific regions within each of a sequence of frames.